Climate change report: live reaction to IPCC conclusions

On Friday, scientists in Stockholm presented the most exhaustive and authoritative state of climate science to date. Follow our live news and reaction as the UN's climate science panel publishes the first part of its fifth assessment report (AR5)

Scientists in Stockholm are due to present the most exhaustive and authoritative state of climate science to date. Follow our live news and reaction as the UN's climate science panel publishes the first part of its fifth assessment report Photograph: Julien Behal/PA

We'll cover further reaction to the report and analysis of the document on our IPCC page – head there for the latest updates.

4.54pm BST

Met Office on the global warming 'pause'

The Met Office blog has a good post today about whether climate models should have predicted the 'pause' in warming that's been discussed in light of the IPCC report:

The IPCC model simulations are projections and not predictions; in other words the models do not start from the state of the climate system today or even 10 years ago. There is no mileage in a story about models being ‘flawed’ because they did not predict the pause; it’s merely a misunderstanding of the science and the difference between a prediction and a projection.

As the IPCC states in line with our three papers on the pause, the deep ocean is likely a key player in the current pause, effectively ‘hiding’ heat from the surface. Climate model projections simulate such pauses, a few every hundred years lasting a decade or more; and they replicate the influence of the modes of natural climate variability, like the Pacific Decadal Oscillation (PDO) that we think is at the centre of the current pause.

For more on this subject, see this earlier post, which includes the same point from our head of environment, Damian Carrington, on the role of the oceans.

4.50pm BST

More from the climate sceptics

Suzanne Goldenberg notes that the head of the Heartland Institute in the US has rubbished the IPCC while at the same time admitting he hasn't even read today's summary report yet. She writes:

Its president, Joe Bast, said he had not yet read the report and did not directly address any of the findings but noted: “Over the history of the IPCC, each report has expressed a higher level of alarmism and a higher level of confidence in its certainty that man-made global warming will be harmful.”

4.43pm BST

Suzanne Goldenberg in the US has been digging into this question of how much carbon we can 'safely' burn.

She writes:

One of the most striking findings of the IPCC report is the idea of a carbon budget, and how quickly time is runniing out before we are locked into dangerous climate change – just 30 years.

Advances in climate-carbon models since 2009 mean that scientists are now able to draw a direct relationship between cumulative carbon emissions and temperature change. Burning more carbon dioxide over time leads to a certain temperature. Burning more than about 1tr tonnes of carbon – the carbon budget – would push warming over the danger point of 2 degrees.

The IPCC said humans have already burned about halfway to 2 degrees.

The World Resources Institute, an environmental think tank, in a blog post this morning said that the rest of that carbon budget will be exhausted by the end of 2044:

"Do the math, and the world only has 469 PgC (petagrams of carbon) left in the budget. This balance puts us on track to exhaust our remaining carbon budget before the end of 2044 under a carbon intensive trajectory.

For context, consider Earth’s increasing pace of emissions: While the first half of the entire global carbon budget was used up over 250 years, the second half of the budget would be used up in only about three decades if emissions continue unabated.”

Kelly Levin, the WRI associate who wrote the blog post, put it in even simpler in a conversation just now.

“This is kind of like a chequing account and when you have spent it all you have no money left. But unlike a bank, where there is a small fee for bouncing a cheque, the climate has much more significant consequences,” Levin said.

She said the finding underscored the need for early climate actions to meet 2020 and 2030 reductions targets which would help slow down emissions, and buy more time.

And to carry the personal finance analogy even further, Levin notes that there is actually less in the account than it might seem. The carbon budget does not take into account greenhouse gas emissions from non-carbon sources.

“The trillion tonne budget is just with CO2. When you add in non-carbon dioxide emissions the budget drops to 800 PgC of carbon which leaves us only with 269PgC in the budget, which means we exhaust the budget 10 years earlier,” Levin said.

The world cannot afford to bunch much more carbon, according to the IPCC and WRI. Photograph: AP

Updated at 4.51pm BST

4.22pm BST

Business reaction

Here's some more reaction from a business perspective, with PwC dryly noting that questions such as as how much heat is being absorbed the oceans are still "not the language of business decisions", and that the "communication divide" between science and business needs to be bridged.

“The IPCC’s report re-confirms the necessity of urgent action on climate change. Business as usual is not an option. Unchecked climate change will increase the frequency and severity of extreme weather events, harming societies and causing ever steeper economic losses.

“The substantial and sustained cut in greenhouse gas emissions called for by the IPCC to avert dangerous warming will only be achieved with determined leadership at a policy level. Transitioning to a low-carbon economy requires strong, long-term climate and energy policies which breed confidence and spur investment. At the moment, inconsistent and unreliable policy signals are deterring investors and hampering investment in low-carbon energy solutions.

“The report also serves as a clear reminder that climate change poses a serious and growing risk to the pensions and investments of people everywhere. As preparations continue for the meeting in Paris in 2015 at which a global deal is expected to be agreed, policymakers have a real opportunity to show bold leadership on climate change ahead of that date.

"When it comes to climate change the world is like a 40 year old smoker. It's not too late for us to give up but it will get harder and more costly each year we delay. When scientists proved the link between smoking and cancer the message was clear: stop smoking. But when it comes to climate change and burning fossil fuels the scientists' warnings have to date been by and large ignored. Progress has been made but not at the pace required by the science.

“We welcome this latest scientific assessment from the IPCC and encourage businesses to look at the enormous commercial opportunities from taking early action and putting sustainability inside their operations. We know from our work with thousands of companies around the world that those that do act early are benefiting in lower energy costs and new business opportunities from a move to a sustainable, low carbon economy. ”

“There’s no doubt that the communication and the language of climate change play a part. Science debates have alienated many from the real issues. In reality, when working on climate risk assessments with companies, I don’t hear much debate about climate sensitivity or the heat of the ocean in 50 years’ time. It’s not the language of business decisions.

Instead, companies talk in terms of operational performance, asset management, business continuity, security of supply of commodities, energy and water, workforce health and well-being. How will investment in resilience and climate mitigation today, show a rate of return in the future? It’s okay that there are many uncertainties - businesses are experts at making decisions around uncertainty, and in scenario planning. Bridging this communication divide will be critical for action.”

Updated at 4.35pm BST

4.08pm BST

Video from Stockholm

We've just published some video highlights of this morning's IPCC press conference, which includes Ban Ki-moon's message, the IPCC's chairman Rajendra Pachauri and co-chair of the report, Thomas Stocker

A major international report on climate science is presented by some of the world's leading scientists on Friday in Stockholm.

3.58pm BST

The view from China

"In China we need to do our own part to try to combat global climate change. We also have to take measures to adapt to this [the impacts of climate change] just like many other countries.""One thing most people would agree is that climate change would add further uncertainties to our already quite tight water supply situation in China."

“I hope to see an integrated solution created to deal with both the local pollution problem and the global climate change problem. Much of these two problems have a similar source, fundamentally it is our energy source that is predominantly dependent on coal, China burns half of the world’s coal. That is the source of the problem for our local smog problem and also for our climate change contribution. We need to deal with the coal issue."

Greg Barker – 'we shouldn't be listening to one or two sceptical voices'

There are very few people now who deny that climate change is happening at all. The overwhelming majority of the world's leading scientists have come together, scientists that specialise in climate science to produce this comprehensive report that's more authoritative than any report that's gone before it. When every country signed up the UN agrees climate change is happening and all the major economies agree that we are causing that to happen and that we need to take action, I think we need to be listening to them, rather than the one or two sceptical voices.

The full clip, where he also talks about fracking, is below.

Greg Barker on 5 News

3.44pm BST

Rainy Britain

In case you were wondering what all this means for the UK, Fiona Harveyhas been talking to the Met Office to find out. While today's IPCC report doesn't specifically go into the impact of climate change on the UK, the Met's Peter Stott has parsed what its projections mean – and it's basically a lot more rain.

Stott said: "There is an increased risk of extremes. As the atmosphere warms, it can hold more moisture, so there is more to fall when there are conditions that produce rain."

Those extremes would be reflected in temperature rises too, he said: "The warmest days will become hotter than they would have been."

Flooding may become more frequent in the UK as climate change turns the weather extreme. Photograph: Daniel Berehulak/Getty Images

Global warming 'pause'?

My colleague Damian Carrington has written a blow-by-blow post tearing the argument apart:

This willful idiocy is based on the fact that air temperatures at the Earth's surface have more or less plateaued since the record hot year in 1998.

What critics choose to ignore is that of all the extra heat being trapped by our greenhouse gas emissions - equivalent to four Hiroshima nuclear bombs every second - just 1% ends up warming the air. By choosing to focus on air temperatures critics are ignoring 99% of the problem.

Are scientists certain that global warming has continued unabated over the last 15 years? Yes. "The best satellite data we have shows that there is still more energy going into the climate system than is going out, because of greenhouse gases in the atmosphere," said Ed Hawkins, at the University of Reading. Another Reading scientist, William Collins, said: "The climate has warmed over the last 10 years, the models are not wrong on the total heat being added."

So where is all the heat going? About 93% goes into the oceans, much of which were largely unmonitored until the 2000s, 3% into land and 3% into melting ice.

Undue focus on the air temperature plateau is cretinous for several more reasons.

David Cameron 'welcomes IPCC report'

A Downing Street source tells me that "the prime minister welcomes the report, and has noted what it has to say about 95% certainty [that human activities are responsible for the warming the planet has experienced]."

David Cameron with huskies in Svalbard, Norway in 2006, part of his bid to rebrand the Conservative party as eco-friendly. Photograph: Reuters

2.59pm BST

Liberal Democrats

Here's the Liberal Democrat energy and climate secretary, Ed Davey, whose official statement, a Lib Dem spokesman tells me, can be taken as representative of the party's position:

The message of this report is clear - the Earth’s climate has warmed over the last century and man-made greenhouse gases have caused much of that global warming. The gases emitted now are accumulating in the atmosphere and so the solutions must be set in motion today. The risks and costs of doing nothing today are so great, only a deeply irresponsible government would be so negligent.

Ed Davey MP. Photograph: Murdo MacLeod

Updated at 3.42pm BST

2.53pm BST

More Labour reaction

Following Ed Miliband's tweet of support earlier, Luciana Berger, the shadow energy and climate secretary, has put out this longer statement, having a pop at environment secretary Owen Paterson's climate beliefs in the process:

Today's IPCC report is a stark reminder from the world's leading climate experts of the scale of the challenge we face to preserve our planet for future generations.

David Cameron promised his would be the greenest government ever, but he is failing to show the leadership we desperately need to tackle climate change both at home and abroad. On his watch we have an environment secretary who doesn't believe in climate change, our carbon emissions are rising rather than falling and the government has failed to set a target a clean up our power system by 2030.

With the 2015 Paris climate conference only two years away, it is vital that Britain makes every diplomatic effort in the coming months to help secure a new global and legally binding climate change agreement. Scientists have reached an agreement. Governments and policymakers must show they can do the same and take action now.

Some more reaction from the world of finance, courtesy of Suzanne Goldenberg in the US:

Mindy Lubber, president of the sustainable investor network, Ceres, said the report provided even greater certainty about climate change risks, which would push companies to act. She said companies with global supply chain, such as apparel companies which rely on cotton, would look to the report to guide their response to climate change.

“The key is beyond the science, climate change disrupts every aspect of the global economy including supply chains, global commodities, and the insurance industry which is seeing exponentially larger losses because of the weather,” Lubber said....“ Smart companies who have to depend on commodities are starting to care more and more about climate change. Their bottom line now depends on that,” she said.

“The IPCC report for all of us should be a statement of the urgency to take action not just by activists, but by companies and by investors.”

2.24pm BST

How the UK media has covered the IPCC report

The report is the top item on all the major newspapers and news sites in the UK, except for the Daily Mail, which is leading with photos of topless feminist protesters, and has buried the story down four or five screen’s worth of scrolling.

The BBC are leading on the line that scientists are 95% certain humans have caused the global warming experienced so far. Matt McGrath, the reporter, highlights a good line I missed from the press conference:

“Speaking at a news conference in the Swedish capital, Prof Thomas Stocker, another co-chair, said that climate change "challenges the two primary resources of humans and ecosystems, land and water. In short, it threatens our planet, our only home". ”

The paper's Ben Webster focuses on certainty regarding humanity's role in warming we’ve seen so far. Later on, the story goes into the impacts the IPCC spell out:

The study predicts that temperatures are set to rise by more than 1.5C above pre-industrial levels by the end of the century without ambitious action to tackle emissions, and could rise by over 4C if emissions continue to increase.

Storms will become more intense and frequent, sea levels will rise by between 26cm (10in) and 82cm (32in) by the end of the century and the oceans will become more acidic, the assessment projects.

The Telegraph leads on humanity's role in warming, with none of the paper's usual note of climate scepticism, which often worms its way into news stories. For example, a Telegraph news report last week described the IPCC report as “seen as the gospel of climate science and is cited to justify fuel taxes and subsidies for renewable energy."

Today's story has some insight into the discussions this week on the summary report's final wording:

“The discussions, which took place at a brewery-turned-conference facility in central Stockholm were frustratingly slow but there is understood to have been little of the infighting between nations that has characterised past meetings.

One delegate told the Telegraph on Thursday night: "The good news is that the Saudis are not objecting to every word like used to happen [at previous meetings].

"It is pretty tame compared to the early years of the IPCC when you used to have a real scrum between people like the Chinese, who could be quite difficult. There is no-one in there saying climate change isn't real."

Except, if you were following our coverage of the press conference earlier or have looked at the report, you’ll see that’s not what the IPCC has “revealed” at all. David Rose’s story for the Mail says the IPCC “still could not explain why the world has barely got any hotter in the last 15 years,” though that’s not quite the whole picture. While Thomas Stocker, the co-chair of today’s report, said that there was not enough published scientific literature on the subject of a 'slowdown', he did speculate on why the rate of warming has slowed in recent years.

The Indy's take focuses on how certain scientists are that humans are behind warming. One interesting line here:

“Scientists involved in the talks said governments have been particularly careful about the wording of this report to make it as difficult as possible for climate sceptics to capitalise on any errors.”

Though it's not clear whether today's report will silence doubters. Pachauri admitted as much earlier at the press conference, when asked if the report would silence climate sceptics:

Business reaction

The IPCC summary for policy holders released this morning is prepared specifically for government, but it will also guide decisions in the business community.

Nick Robins, who heads the climate change centre at HSBC, said business leaders will be studying the findings closely – especially those involved in managing risk.

“The key thing now is taking this very high quality science and then translating it into a risk management strategy for business which is question both of size of impact and the probability of impact,” he said.”We actually need to avoid not just the most likely scenarios but those long tail high impact scenarios as well.”

Even if warming is kept to 2C – which the IPCC report made clear would only happen with extreme effort – the risk of climate disruption was still too high for the insurance industry and for investment managers, Robins said.

“If you look at those sectors they are well in advance of many sectors thinking about this issue. Those are the people in the economy we pay to manage risk for us,” he said.

Robins said the report is likely to provide further impetus for the move to a low-carbon economy – despite all the talk of a brief hiatus in warming.

“There are multiple drivers now that give us more confidence that we are going to accelerate the drive to a low carbon economy. We have much better science, and we are in a much better position to deploy solutions.”

“That means that rather than a pause in action we can go much quicker.”

Solar panels in Bad Hersfeld, Germany. Nick Robbins of HSBC says solar power and other 'solutions' to climate change are coming down in cost Photograph: LISI NIESNER/REUTERS

Updated at 2.04pm BST

1.22pm BST

The climate sceptics have started to lash out, our environment editor John Vidal observes. Peter Miller, writing on the Watts Up With That blog says:

“I am watching the IPCC farce right now, North Korea would be proud of this type of stitch up. Interestingly, there is absolutely no applause for any of the speakers.... Natural climate cycles remain a heresy. ..This is little more than a jamboree for quasi-government bureaucrats.

One thing is clear: the version of events you will see and hear in much of the media, especially from partis pris organisations like the BBC, will be the opposite of what the IPCC’s Fifth Assessment Report actually says.... At the heart of the problem lie the computer models which, for 25 years, have formed the basis for the IPCC’s scaremongering: they predicted runaway global warming, when the real rise in temperatures has been much more modest. So modest, indeed, that it has fallen outside the lowest parameters of the IPCC’s prediction range. The computer models, in short, are bunk.

I've seen various other bits and bobs in the climate sceptic blogosphere, but no one there seems to have plucked a 'gotcha' from today's report, yet.

UK-based Bishop Hill, run by Andrew Montford, has this, labelling the reporters at the IPCC press conference "environmentalists" except for the Mail's David Rose (see earlier post):

The general theme of obscurantism runs across the document. Whereas in previous years the temperature records have been shown unadulterated, now we have presentation of a single figure for each decade; surely an attempt to mislead rather than inform. And the pause is only addressed with handwaving arguments and vague allusions to ocean heat.

From the questions asked by journalists at the press conference, few cared about the science and the contradictions in what they were being told. The press corps are, almost to a man (and woman) environmentalists and only interesting in decarbonisation. The exceptions were David Rose and the guy from the Economist. So it is very uncertain that the problems in the WGI report will make the mainstream of public discourse.

“The U.S. is already making real progress in the fight against climate disruption by reducing America’s dependence on dirty fossil fuels like coal and oil, while boosting clean energy like wind and solar. These are common sense climate solutions that benefit our economy, health and future, but we need to do more to speed the transition to clean energy and keep dirty fossil fuels, including natural gas, where they belong - in the ground.

“The findings in this report confirm that we need the safeguards to curb climate-disrupting carbon pollution from new power plants that the Obama Administration proposed last week. And we cannot stop there. To cement his legacy and protect future generations, President Obama must reject the expansion of dirty fossil fuels like coal, oil, and natural gas -- as well as dangerous nuclear power -- and move full-speed ahead to grow the job-creating clean energy economy.”

Frances Beinecke, president of the Natural Resources Defence Council, also had a shout-out for Obama

“The science is clear: We are altering the climate. That must be corrected. President Obama’s common-sense climate action plan will help. His administration is setting limits on carbon pollution from new power plants. That’s a critical step to fulfilling our obligation to protect our children from climate change.”

Democrats in Congress also saw the IPCC report as a chance to support Obama's climate plan. Barbara Boxer, the California Democrat who is the biggest champion of climate action in the Senate, said:

“We have seen the dangerous impacts of climate change all around us – from record high temperatures in the U.S., to severe wildfires in California and other western states, to flooding of biblical proportions, to shrinking Arctic sea ice and rising sea levels. This landmark report underscores the importance of the Obama Administration’s efforts to curb carbon pollution, and I will do everything in my power to support the Administration in their efforts to address the dangerous impacts of climate disruption.”

Updated at 1.09pm BST

1.03pm BST

What's changed since the IPCC's last major report six years ago?

Damian Carrington has been talking to climate scientists at a briefing in London. He asked them what the biggest change has been since the IPCC’s last major report in 2007:

Prof Stephen Belcher, head of the Met Office Hadley Centre:

"The clear cut statement by the IPCC that the "human influence on the climate is clear" is a landmark"

Prof Tim Palmer, Royal Society research professor, University of Oxford:

"The report is further reinforcement that there is an unequivocal risk of dangerous climate change"

"Carbon dioxide has probably not been this high in the atmosphere for 3 million years. We understand the greenhouse effect, so what more information do people want?"

Carrington also notes that Prof David Mackay, chief scientific adviser to the department of energy and climate change, has been in place for four years but never met David Cameron, George Osborne or Owen Paterson.

Updated at 1.12pm BST

12.52pm BST

Responses from perspectives of the developing world, science and youth

Saleemul Huq, senior fellow in the thintank International Institute for Environment and Development’s climate change group and coordinating lead author in Working Group II of the IPCC says:

The IPCC has confirms what many millions of people in the developing world are already well aware of, namely that the weather patterns have already changed for the worse. People in richer countries are vulnerable too, as recent floods, droughts and storms in Europe, North America and Australia have shown, but because of political inertia and powerful vested interests that have dominated media narratives for decades, they are less aware of the links between these impacts and their carbon emissions. Climate change affects us all and we must tackle it together.

It is becoming increasingly clear that we are responsible for warming of the Earth primarily due to the burning of fossil fuels. Predicting the implications of this or how the picture will change in the future are big challenges for scientists and today’s report by the IPCC, whilst recognising uncertainties, gives us the best possible insight into what may lay ahead. Those who predict imminent disaster are probably overstating the case, but equally those who claim that we can carry on regardless are likely to be burying their heads in the sand.

Today’s report shows the last 30 years were the warmest in 800 years. In that time our generation have grown up and scientists the world over have worked tirelessly to explain the problem. World leaders have barely lifted a finger. Our generation is organising a powerful global movement for change and we need world leaders to follow.

Miliband responds

Labour leader Ed Miliband tweets that the IPCC report shows the "urgent need for long-term policy to tackle it." I'm sure I'm reading too much into it and it's pretty clear what Miliband means here, but "long-term", seems a slightly odd choice of phrase given today's report highlights is the urgency for short-term action, though obviously carried on through to the longterm.

Pachauri, the IPCC's chairman, said earlier: "There is a need for us to reduce emissions of greenhouse gases, substantially, if we want to stabilise the Earth's climate."

Ed Miliband (@Ed_Miliband)

IPCC report is a stark reminder of central challenge of global warming, its human cause and urgent need for long-term policy to tackle it

The view from the US

Our US environment correspondent, Suzanne Goldenberg, has been speaking to Michael Oppenheimer, a scientist at Princeton University, who she describes as "one of the leading voices for climate action in America for the last 30 years." He was a co-author on the next section of the IPCC report due out in the spring.

He said the report had a clear message for governments:

Taking the big picture view it says the earth has become significantly warmer and that it is extremely likely that most of the warming of the past 60 years is due to human made building up of greenhouse gasses.

The most important message probably is that at the current rate humanity is going to blow through the 2 degrees celsius target governments have set as an indicator of where the warming gets dangerous. One of the most important points of the report is that without extreme effort we are just going to land in the danger zone.

Goldenberg adds:

Oppenheimer said this report goes out of its way in emphasising that humans have already reached the halfway point in terms of the trillion tonne limit, the cumulative amount of carbon emissions that would raise temperatures above 2C.

Once that trillion tonne limit is crossed, the risks begin to pile up: very high sea-level rise, threats to food supply, frequency of heat waves, he said.

Finally, Oppenheimer says:

We have already emitted about half that amount, and we could emit the other half in the next 25 years. We are on the proverbial supertanker. It's going to be very difficult to turn it around, and the report does make the point very starkly that the 2 degree target is not going to be avoided if we just keep doing what we are doing.

An aerial view of a farm near Rock Port, Missouri submerged in Missouri River flood waters Photograph: STR/Reuters/Corbis

12.08pm BST

Hague says delay on climate action will cost future generations

Foreign secretary William Hague, who has been perhaps one of the most progressive voices on climate change in the coalition since it came to power in 2010, has put out this statement. My emphasis in bold.

The UN Intergovernmental Panel on Climate Change’s latest assessment of the science confirms that climate change is already happening, as a result of human activity. The odds of extreme weather events, which threaten lives and property, have increased. Sea levels are rising, and ice is melting faster than we expected. The IPCC’s report makes clear that unless we act now to reduce carbon emissions, all this will continue to worsen in coming decades. Governments, businesses and individuals all have a responsibility to tackle climate change. The longer we delay, the higher the risks and the greater the costs to present and future generations.

British Foreign Secretary William Hague Photograph: PETER FOLEY/EPA

Hague recently appointed former government scientific adviser Sir David King as his climate adviser. King's approach to the UN climate talks, which today's science will feed directly into, is controversial in some quarters, as we reported earlier this month:

King's reappointment to a government role – primarily to guide the UK's stance in international climate negotiations, but he also to advise on aspects of the UK's greenhouse gas reduction – will cause consternation among some green campaigners, because of his controversial views on the progress of UN climate negotiations. He does not believe that the current style of talks, aimed at producing a global agreement similar to the Kyoto protocol of 1997, will bear fruit in the way their backers hope.

His view is that the US, which declined to ratify the Kyoto protocol, will not sign up to a legally binding international treaty on climate change because that would require a majority in favour in Congress, which he sees as unlikely. At the same time, he notes, China – the world's biggest emitter – is refusing to countenance a global agreement if the US stays outside.

King said that a "considerably more creative" solution was needed.

This would be most likely to take the form of a "bottom-up" arrangement by which each country could set its own targets on greenhouse gas reduction, and meet them at a national level, rather than having to submit to internationally set goals.

12.00pm BST

Twitter roundup

Former US vice-president Al Gore calls today's report "an important milestone." Here's more reaction from Twitter:

Al Gore (@algore)

The latest report by the IPCC is an important milestone in the study of climate science. http://t.co/kcgjnHSfsA

IPCC report sends out 'unequivocal' message on climate change

World leaders must now respond to an "unequivocal" message from climate scientists and act with policies to cut greenhouse gas emissions, the United Nations secretary-general urged on Friday.

"The heat is on. We must act," said Ban Ki-moon, as he invited world leaders to a special summit next year to forge a global agreement on emissions.

The world's leading climate scientists, who have been meeting in all-night sessions this week in the Swedish capital, said there was no longer room for doubt that climate change was occurring, and the dominant cause has been human actions in pouring greenhouse gases into the atmosphere.

In their starkest warning yet, following nearly seven years of new research on the climate, the Intergovernmental Panel on Climate Change (IPCC) said it was "unequivocal" and that even if the world begins to moderate greenhouse gas emissions, warming is likely to cross the critical threshold of 2C by the end of this century. That would have serious consequences, including sea level rises, heatwaves and changes to rainfall meaning dry regions get less and already wet areas receive more.

In response to the report, the US secretary of state, John Kerry, said in a statement: "This is yet another wakeup call: those who deny the science or choose excuses over action are playing with fire."

What we've learned this morning

Scientists are more certain than ever that humanity is to blame for rising temperatures. The head of the UN WMO said "it is extremely likely that changes in our climate system in the past half century are due to human influence." The report says: "Human influence on the climate system is clear. This is evident from the increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed warming, and understanding of the climate system."

We're likely to go over rises of 2C by 2100, the threshold of warming that governments have pledged to hold temperatures to and beyond which dangerous consequences including drought, floods and storms are expected. "What is very clear is we are not" on the path to keeping temperatures below 2C, said Thomas Stocker, one of the co-chairs of today's report. Global temperatures are likely to rise by 0.3C to 4.8C by the end of the century, the report said.

Sea level rises are coming. "Global mean sea level will continue to rise during the 21st century," says today's report, by a further 26-82cm by 2100, but Stocker said "there is no consensus in the scientific community over very high sea level rises."

Scientists said that claims that the rate of temperature rises in the last 15 years has slowed did not affect the big picture and temperatures are going up in the longterm. Climate trends "should not be calculated for periods of less than 30 years," said Stocker.

The amount of carbon the world can burn without heading for dangerous levels of warming is far less than the amount of fossil fuels left in the ground. "The IPCC carbon budget to stay below 2C is 800-880 gigaton carbon. 531 GTC had already emitted by 2011. So we have 350GTC left, which is much less than the carbon stored in fossil fuel reserves," notes our correspondent Fiona Harvey.

11.17am BST

Green party leader, Natalie Bennett, has this to say. I've not seen any statements from the big three parties yet.

The IPCC conclusions are clear. The scientific debate is over: the scientific conclusion is we need to take action now to avert catastrophic climate change.

"What needs to begin now is a serious, urgent debate about political and policy action.

"With the Climate Change Act in place, Britain is in a position to be a global leader, which also gives us the opportunity to benefit from a range of new low-carbon industries."

Alison Doig, Christian Aid's senior climate change adviser, said:

Scientific evidence confirms that man-made climate change is a reality and that, without urgent action globally, the impacts will get worse. The time for debate is over, it is time to act.

"Rising temperatures will bring enormous economic and human cost. We need to support countries and communities most at risk in preparing to cope with disaster, to lessen the impacts of extreme weather events and help communities recover more rapidly when they do occur.

"The implications of melting ice caps and rising sea levels for people and economies around the world will be enormous, but it is the poorest and most vulnerable people who depend on the land and sea for their living who will be most affected."

Natalie Bennett leader of the Green party in England and Wales who has claimed that British politics is heading for "big shifts" in the next few years as voters abandon the mainstream parties in the search for "new answers". Photograph: Max Nash/PA

Lord Deben, aka John Gummer, the former environment secretary and current chair of the government's climate advisers, the Climate Change Commission, tweets that:

It illustrates pretty starkly the enormous challenge of avoiding temperature rises below 2C – something that Pachauri and others alluded to at the press conference this morning.

How will it get in your lifetime?

10.58am BST

"It's the science, stupid" says EU climate chief

Connie Hedegaard, the EU's climate action commissioner, is referring here to the fact today's IPCC report says human activities are 95% likely to be behind the warming we're experiencing, up from the 90% the IPCC said in 2007.

The fifth Intergovernmental Panel on Climate Change report states with 95% confidence that humans are the main cause of the current global warming. Many media outlets have reported that this is an increase from the 90 percent certainty in the fourth IPCC report, but actually the change is much more significant than that. In fact, if you look closely, the IPCC says that humans have most likely caused all of the global warming over the past 60 years.

Updated at 11.14am BST

10.54am BST

Humanity's role

The Economist asks: how can we be more certain about human role in the warming?

The press conference has just finished. I'll have more reaction for you soon.

10.52am BST

The report's key messages

These are taken straight from the report - I think I've got all of them:

Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased

Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850. In the Northern Hemisphere, 1983–2012 was likely the warmest 30-year period of the last 1400 years

Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010 (high confidence). It is virtually certain that the upper ocean (0−700 m) warmed from 1971 to 2010, and it likely warmed between the 1870s and 1971.

Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent (high confidence)The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia (high confidence). Over the period 1901–2010, global mean sea level rose by 0.19 [0.17 to 0.21] m

The atmospheric concentrations of carbon dioxide (CO2), methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years. CO2 concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions. The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification

Total radiative forcing is positive, and has led to an uptake of energy by the climate system. The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of CO since 1750

Human influence on the climate system is clear. This is evident from the increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed warming, and understanding of the climate system

Climate models have improved since the AR4. Models reproduce observed continental-scale surface temperature patterns and trends over many decades, including the more rapid warming since the mid-20th century and the cooling immediately following large volcanic eruptions (very high confidence)

Observational and model studies of temperature change, climate feedbacks and changes in the Earth’s energy budget together provide confidence in the magnitude of global warming in response to past and future forcing.

Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes. This evidence for human influence has grown since AR4. It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.

Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.

Global surface temperature change for the end of the 21st century is likely to exceed 1.5°C relative to 1850 to 1900 for all RCP scenarios except RCP2.6. It is likely to exceed 2°C for RCP6.0 and RCP8.5, and more likely than not to exceed 2°C for RCP4.5. Warming will continue beyond 2100 under all RCP scenarios except RCP2.6. Warming will continue to exhibit interannual-to-decadal variability and will not be regionally uniform

Changes in the global water cycle in response to the warming over the 21st century will not be uniform. The contrast in precipitation between wet and dry regions and between wet and dry seasons will increase, although there may be regional exceptions

The global ocean will continue to warm during the 21st century. Heat will penetrate from the surface to the deep ocean and affect ocean circulation.

It is very likely that the Arctic sea ice cover will continue to shrink and thin and that Northern Hemisphere spring snow cover will decrease during the 21st century as global mean surface temperature rises. Global glacier volume will further decrease.

Global mean sea level will continue to rise during the 21st century. Under all RCP scenarios the rate of sea level rise will very likely exceed that observed during 1971–2010 due to increased ocean warming and increased loss of mass from glaciers and ice sheets.

Climate change will affect carbon cycle processes in a way that will exacerbate the increase of CO2 in the atmosphere (high confidence). Further uptake of carbon by the ocean will increase ocean acidification.

Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond. Most aspects of climate change will persist for many centuries even if emissions of CO2 are stopped. This represents a substantial multi-century climate change commitment created by past, present and future emissions of CO2.

Updated at 11.19am BST

10.43am BST

Pilita Clark at the FT says the summary's reference to the slowdown in temperatures over the last 15 years appears to have been changed this week.

Stocker says:

There was made a change in placement or messages regarding this issue of climate change

I can tell you in these four days all of my colleagues present here in Stockholm were challenged

Challenged on a really high level but the governments to tell in simple words what our assessment is

I am extremely proud to say we have kept the 18 key messages

We have also kept all the figures that were proposed to inform in a comprehensive way policymakers but also the wider public

What we have come out with has clearer and more understandable language, but the essence of what we have come out with has not changing whatsoever

Some of the broader questions you are asking, go far beyond temperature changes, so I want to bring those reports to your attention as well

10.38am BST

Some more reaction to the report, from climate scientists.

Professor Corinne Le Quéré, Director of the Tyndall Centre for Climate Change Research and a lead author on AR5, said:

"This is not just another report, this is the scientific consensus reached by hundreds of scientists after careful consideration of all the available evidence. The human influence on climate change is clear and dominant. The atmosphere and oceans are warming, the snow cover is shrinking, the Arctic sea ice is melting, sea level is rising, the oceans are acidifying, and some extreme events have increased. CO2 emissions from burning fossil fuels need to substantial decrease to limit climate change."

Prof Matthew Collins, Joint Met Office Chair in Climate Change at the University of Exeter and Coordinating Lead Author of Chapter 12 in today’s report, said:

“Further emissions of greenhouse gases will cause further global warming. The Arctic will warm most rapidly and the land will warm more than the ocean. There will be more hotter and fewer cold days. Mid-latitude areas that currently experience high rainfall will get more. Sea levels will continue to rise and snow and ice will melt back. If we follow the highest scenario of future greenhouse gases, the Arctic is expected to be ice-free before the middle of the 21st century.

“Avoiding 2 degrees of warming since preindustrial times will be very tough. We have already ‘spent’ more than two thirds of the CO2 emissions that we can afford to spend.”

10.36am BST

Bloomberg says if a 15 year period is less relevant and 30 years is what you'd normally look at, why did the IPCC even bother mentioning a 15 year period in the report?

Stocker answers:

It's important to look at the longer term

The financial crisis has reduced emissions by just a year

"I've been up for 52 hours with 6 hours sleep", Stocker repeats.

Currently what is very clear is we are not on that path [to 2C]

It is clear that this question [of how much the rate of warming has slowed down in the past 15 years] is very interesting for the scienitsts, but there are not many studies that would enlighten us... but when one analyses longer periods, it's not such an unusual case

In particular it's worth noting 1998 [when observers are counting the 15 year period from]... was characterised by the second strongest El Nino year in the twentieth century [which has a warming effect]... that, coinciding with a series of medium to low strength volcanic eruptions over the last 5-10 years, plus La Nina [which both have a cooling effect], we are just in a situation where if you cast three dice, you get three faces of six or three faces of one

Jarraud reiterates that picking 1998, an exceptionally hot year, is not a meaningful way to measure recent warming.

10.28am BST

Stocker on sea level rises

There is no consensus in the scientific community over very high sea level rises

10.27am BST

Chinese co-chair Qin Dahe says

This science report has a big impact on Chinese way of life

If every Chinese person has a lifestyle like a US person, it would... be catastrophic

Updated at 11.57am BST

10.25am BST

Green groups' reaction

“There are few surprises in this report but the increase in the confidence around many observations just validates what we are seeing happening around us. Since the IPCC issued its last big report in 2007, terrestrial glacier loss and sea-level rise has dramatically accelerated; the Arctic summer sea ice losses are higher than originally projected and the last decade was the warmest since 1850... Whichever facts may be discussed, debated or distorted, we cannot ignore the reality that we must act or face frightening new impacts. We know that most of the pollution that causes climate change comes from burning fossil fuels. WWF calls on governments and investors to stop investing in dirty energy and start an immediate and just transition by investing in renewables."

Greenpeace

Stephanie Tunmore of Greenpeace International, says:

"The only logical response to a warning of this magnitude is immediate action. Unfortunately those who are taking this action are now in prison in Russia, while those that are most responsible are protected by governments around the world."

Friends of the Earth

Their executive director, Andy Atkins, brings it back to what the report means for the UK:

“Scientists are now as convinced that humans are causing climate disruption as they are that smoking causes cancer - politicians can’t continue to stand idly by while the world goes spinning towards climate catastrophe.

“Tough action is urgently needed to end the planet’s dangerous fossil fuel fixation and to develop the huge job-creating potential of renewable power – with developed nations like Britain taking the lead.

“The Coalition Government must seize the initiative, starting with a 2030 decarbonisation target for the power sector.

“Faced with overwhelming scientific evidence, supported by the public, there is no excuse for failing to act on climate change.”

Updated at 10.37am BST

10.21am BST

Jarraud chips in to reply to Rose, says it is an "ill-posed question."

You should distinguish the ability to predict temperature 10 years in advice, from the ability to predict 20-30 years in advance.

The best timescale to look at at is 30 years, he says. Rose is referring to the last 15 years.

10.17am BST

David Rose of the Mail on Sunday asks: How much longer will the current hiatus [in temperature rises] have to continue for you to conclude there is something wrong with your models?

Stocker answers:

These climate models have shown remarkable agreement with the longer term trends that we have observed

This gives us confidence

There is an entire chapter in our assessment that concludes models have improved in their performance

Estimates are extremely unlikely to be below 0C

This report has now declared a best estimate [of temperature rise]

Rose says his question has not been answered.

Stocker replies that he cannot give a number today.

Rose was the journalist who wrongly claimed earlier this month that the rate of warming experienced recently had been half of what scientists had predicted. He had to retract the claim.

Updated at 10.19am BST

10.11am BST

How much carbon can we emit?

On this question of how much more carbon we can burn without having dangerous levels of warming (carbon budgets), Fiona Harvey points out:

The IPCC carbon budget to stay below 2C is 800-880 gigaton carbon. 531 GTC had already emitted by 2011. So have 350GTC left, which is much less than the carbon stored in fossil fuel reserves.

10.10am BST

Stocker is talking more on carbon budgets:

Certainly at the level of this SPM [summary for policymakers], we did not communicate specific numbers for when and how emissions should be reduced.

We given total amount of carbon that cannot be exceeded to stay below, say, 1.5C or 2C

These values need to be taken in the context of the carbon emitted already, up to now

We know for example to stay below 2C, another target that is negotiated or discussed at the UNFCCC, we cannot emit more than 1,000 billion tonnes of carbon, of which already 54% have been emitted

Pachauri notes that working group 3, which publishes its work next year, will home in on this area.

10.07am BST

Our Fiona Harvey asks Pachauri and Stocker: on the question of carbon budgets [i.e. how much carbon can be burned if the world wants to keep temperatures between certain limits, such as 2c], it has the clear implication we cannot burn our fossil fuel reserves, doesn't it?

Pachauri replies:

An extremely effective instrument would be to place a price on carbon

To some extent, regulations, informing the public would make a difference

But in the ultimate analysis it is only through the market we could get a large enough and rapid enough response

John Kerry: 'climate change is real, it's happening now'

“Boil down the IPCC report and here’s what you find: Climate change is real, it’s happening now, human beings are the cause of this transformation, and only action by human beings can save the world from its worst impacts.

This isn’t a run of the mill report to be dumped in a filing cabinet. This isn’t a political document produced by politicians.

It’s science.”

She says that Kerry also promised US action on the back of the report. The State Department said in a report on Thursday it was on track in its commitment to cut emissions by 17% from 2005 levels.

“The United States is deeply committed to leading on climate change,” Kerry said.

Updated at 11.05am BST

9.54am BST

Stocker has just finished up

We have concluded that in order to limit climate change, it will require continued and substantial reductions of emissions

9.52am BST

Stocker on sea level rises

Another parameter, or variable, that has been very carefully assessed, is sea level.

These curves [for future sea level rises] go up, of course it depends on the scenario, on our choices today, whether sea level rise will be 24cm for the best estimate for the lowest scenario... or the higher value of 40cm or 63cm by 2100

Stocker calls consensus between governments on climate change an 'achievement'

This report consists of over a million words

This report is a report that has undergone thorough review

I can assure you that during the four days, the 110 governments have looked at every single word, at every number that is in this [summary] report

Sometimes paragraphs were discussed over an hour

What I am most proud of is we've gone another step to condensing our messages - we give 18 headline messages on less than two pages in simple, understandable language

This is an achievement

110 governments have found consensus over 18 short headlines

Updated at 9.46am BST

9.39am BST

Thomas Stocker, co-chair of working group one (WG1), is speaking

Climate change is the greatest challenge of our time

That says the Cancun agreement [of 2010]

He says they've only had a few hours sleep over the last two days

This is the first of three assessment reports

Will close with synthesis report in November 2014

In 2009, WG1 has produced an outline of content scientists together with governments approved

It was like a task given to scientists of the world - please tell us what you know of observed climate change

9.35am BST

More from Fiona Harvey, who says the scientists have addressed one of the sceptics' favourite aguments against climate change - the "mediaeval warm period" or medieval climate anomaly of the years 950 to 1250.

The scientists say:

continental scale surface temperature reconstructions show with high confidence multidecadal periods during the medieval climate anomaly that were in some regions as warm as in the late 20th century these regional warm periods did not occur as coherently across regions as tghe warming in the late 20th century (high confidence)

9.33am BST

Today's report has not been as well attended by media as the IPCC's 2007 report in Paris, says Fiona Harvey:

far fewer jounalists, notably more low-key

She adds:

Groups are standing outside the conference centre holding placards saying: Stop the IPCC genocidal agenda and "what the IPCC does not understand: human creativity!" These are sceptics campaigning against IPCC

Updated at 9.35am BST

9.30am BST

Pachauri has just highlighted this passage in the report, which he calls a "succinct summary of what we are doing to the system:"

Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased

He adds:

I also want to highlight that each of the last three decades has successively warmed at the earth's surface

9.28am BST

Pachauri says this report is informed by new scientific papers and has new authors

[AR5] Authors are bringing in fresh perspectives, they're bringing in new knowledge

We carried out citation of 9,200 scientific publications, roughly two thirds published since 2007

He says they also had over 50,000 comments provided by over a thousand reviewers.

Some of the findings of this report go far beyond what we were able to provide in AR4. I want to pay the highest tribute to scientists who have worked on this report. Symbolic of that is what we have been through in the last four days, we have worked two nights, fairly late at night.

9.25am BST

Rajendra Pachauri, IPCC chairman

We've come a long way [since AR4]

In 2010, Ban Ki-moon and I requested the InterAcademy council to carry out a detailed assessment of IPCC's processes and procedures. They come up with an excellent report. And the governments of the world who are essentially members of the panel, accepted and implemented the measures fully, except for one which had procedural issues.

IPCC press conference webcast

John Vidalhas reported on what consequences the IPCC report spells out for developing countries:

Low-income countries will remain on the frontline of human-induced climate change over the next century, experiencing gradual sea-level rises, stronger cyclones, warmer days and nights, more unpredictable rains, and larger and longer heatwaves, according to the most thorough assessment of the issue yet.

The last major UN assessment, in 2007, predicted runaway temperature rises of 6C or more by the end of the century. That is now thought unlikely by scientists, but average land and sea temperatures are expected to continue rising throughout this century, possibly reaching 4C above present levels – enough to devastate crops and make life in many cities unbearably hot.

As temperatures climb and oceans warm, tropical and subtropical regions will face sharp changes in annual rainfall, says the Intergovernmental Panel on Climate Change (IPCC) report, released on Thursday in Stockholm before online publication on 30 September.

A man rebuilds a house after Cyclone Nargis, which caused devastation in Burma. Photograph: Getty Images

IPCC report available for download

Humans to blame for warming and rise of over 2C expected by end of the century – scientists

Fiona Harvey has filed this story on the report, which should be available online in the next few minutes:

The world is warming, and we are to blame. Already some of the results of this are "unprecedented" and dangerous. If we continue to pour greenhouse gases into the atmosphere, the levels of warming will cause severe problems around the globe, and could soon be catastrophic.

That is the "unequivocal" message from the world's leading climate scientists, who have been meeting in Stockholm this week to thrash out the most comprehensive review to date of our knowledge of climate change.

If the message seems one that has been heard before - scientists have been reporting for more than two decades on the threat of climate change - the import is still of huge significance. Forging a clear agreement on the science of such a vast and complex issue as the whole future of the planet and its life-support systems is no small endeavour, and the report from Stockholm draws on the work of more than 800 scientists and hundreds of research papers.

The scientists also put paid to claims that global warming has "stopped" or "paused". They said: "Each of the last three decades has been successively warmer at the earth's surface than any preceding decade since 1850 in the northern hemisphere [the earliest date for reliable temperature records for the whole hemisphere]."

The scientists have faced sustained attacks from so-called sceptics, often funded by "vested interests" according to the UN, who try to pick holes in each item of evidence for climate change. The experts have always known they must make their work watertight against such an onslaught, and every conclusion made by Intergovernmental Panel on Climate Change must pass scrutiny by all of the world's governments before it can be published.

So their finding that human influence on the climate can no longer be doubted, that the evidence for this is clear in most regions of the globe, and that only drastic cuts in emissions can save us from disastrous consequences is still a powerful one.

"Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system," said Thomas Stocker, co-chair of the IPCC's working group on the physical basis for climate science. "Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions."

Their warning on Friday was sent out to governments around the globe, who convene and fund the IPCC.

It was 1988 when scientists were first convened for this task, and in the five landmark reports since then the research has become ever clearer. Now, scientists say they are certain that "warming in the climate system is unequivocal and since 1950 many changes have been observed throughout the climate system that are unprecedented over decades to millennia". That warning, from such a sober body, hemmed in by the need to submit every statement to extraordinary levels of scrutiny, is the starkest yet.

Climate science has been under attack in recent years, as never before, and the clear statement by the world's foremost experts in the field is the starkest warning to date. Sceptics are likely to seize on aspects of the IPCC report, such as taking the very lowest range of the estimates it has produced for future warming.

The central estimate is that warming is likely to exceed 2C, the threshold beyond which scientists think climate change will start to cause catastrophic and potentially irreversible changes, by the end of this century. That threshold is likely to be reached even if we begin to cut global greenhouse gas emissions, which so far has not happened, according to the report.

"Heatwaves are very likely to occur more frequently and last longer. As the earth warms, we expect to seee currently wet regions receiving more rainfall, and dry regions receiving less, although there will be exceptions," Stocker said.

Atmospheric concentrations of carbon dioxide, methane and nitrous oxide are now at levels "unprecedented in at least the last 800,000 years".

The oceans have acidified as they have absorbed about a third of the carbon dioxide emitted.

Qin Dahe, also co-chair of the working group, said: "As the ocean warm, and glaciers and ice sheets reduce, global mean sea level will continue to rise, but at a faster rate than we have experienced over the past 40 years."

Le Conte Glacier in Alaska Photograph: Ernest Manewal/Purestock/Super

Updated at 9.01am BST

8.51am BST

Here's more insider info from Fiona Harvey in Stockholm:

The Guardian understands that one critical issue that has been satisfactorily resolved is that of the "pause" in the rise in global temperatures in recent years, which has been seized on by sceptics as evidence that warming is not happening. The report will say that transfers of heat to the oceans are partly responsible, and that the observed slowdown in the upward march of temperatures is well within the range of projections from the climate models, which reflect the natural variability of the climate as well as the effects of human interference.

Another key point is the question of a "carbon budget" - the amount of carbon that can be emitted if the world is to avoid the most dangerous levels of warming. The report will quote a figure of 270 petagrams of carbon, equating to 990 gigatons of carbon dioxide, that can be emitted globally by the end of the century. This would require deep cuts in emissions. But the main discussion of carbon budgets will have to wait for the next instalments of the report next year.

Leo Hickman examined the question of a pause in temperature rises for us earlier this year, concluding:

The "global warming has stopped" line from climate sceptics has always hung its hat heavily (and conveniently) on the freakishly anomalous warm year of 1998 as its starting point or baseline. As has been pointed out repeatedly by the Met Office and many climate scientists, this is tantamount to picking the sweetest of cherries. The rate of decadal rise in average global temperatures has clearly slowed over the past decade or so, compared to the previous couple of decades, but to say it has "stopped" altogether seems to be a misleading statistical sleight of hand.

It also strikes me as complacent, or even reckless, to assume that any slowing is proof that global warming is nothing to worry about. As many scientists in the field point out, there are several likely causes - both natural and anthropogenic variables - that could be masking or absorbing the so-called "missing heat", not least the oceans and/or soot released by the burning of coal in fast-industrialising nations such as China. To assume global warming has been falsified is, in my view, a very cavalier, wrong-headed display of long-term risk analysis.

And here's our head of environment, Damian Carrington, on the fact scientists were discussing this issue several years ago:

Why is this report so important? Mark Walport, the government’s chief scientist, was on Radio 4’s Today programme this morning, talking about its significance:

Extremely important moment

The evidence is absolutely rock solid

There is actually a right answer to the question of whether humans are contributing the climate change

I think the terminology of global warming, climate warming isn't the right one it is actually climate disruption

We do know that we've emitted half a trillion tonnes of carbon dioxide

The issue is that scientists have got to communcate this

There are some people who don't want to confront the policy decisions and the easiest way to do that is to rubbish the science

Today also had Jeremy Leggett, the founder and executive chairman of solar power company SolarCentury, talking about the business implications of the report. He mostly spoke about what's being described in some circles as the 'carbon bubble'. That's the idea that if governments acted as seriously as the science being presented today requires, then the investment bubble around fossil fuel companies would be popped, wiping off trillions of dollars in value and causing another financial crash.

Sir Mark Walport, former director of the Wellcome Trust and the UK government's chief scientific adviser, who succeeded Sir John Beddington in April 2013. Photograph: Wellcome

8.21am BST

Our correspondent, Fiona Harvey, writes this from Sweden, where the report's press conference is due to begin within the hour:

The world's media started arriving long before 8am at the old brewery in Stockholm where the world's leading climate scientists have been holed up all night, and for the past four days, hammering out the final details of their message to the world on climate change.

As media and NGOs arrived at the Stockholm waterfront in a grey dawn, the scientists were still locked in their hall making their final deliberations, which were supposed to finish before 8am CET (7am BST).

At shortly after 8.30am CET (7.30am BST), the message came that the gavel had come down. The marathon meeting, intended to be produce the most comprehensive assessment yet of our knowledge of climate change, was finally over.